/Engine/Source/Runtime/Engine/Public/BatchedElements.h
This is for compatibility but should be avoided since it's slower due to conversions.
int32 AddVertex ( const FVector4 & InPosition, const FVector2D & InTextureCoordinate, const [FLinearColor](API\Runtime\Core\Math\FLinearColor) & InColor, [FHitProxyId](API\Runtime\Engine\FHitProxyId) HitProxyId )